The answer isn't what you'd expect

Grab any given cookbook, and you’ll find myriad mentions of eggs, sugar, and wine—all typical recipe fare. But wait. Didn’t you just read last month that sugar is toxic to human cells, and that eggs might up your risk of prostate cancer? As for wine, it either cuts your odds of developing breast cancer, or increases them, but you can’t remember which. Is your cookbook trying to kill you? Or—even worse—is everything we eat associated with this dreaded disease?

It’s a valid question, and one that scientists from Harvard Medical School and Stanford’s Prevention Research Center wanted to answer. So they performed a (much more scientific) cookbook test of their own, choosing 50 random ingredients from the Boston Cooking-School Cook Book.

The team then pored over journals and analyzed studies involving each ingredient and cancer risk. A whopping 80% of the ingredients were included in at least one study linking them to cancer, and half the ingredients were tied to cancer in more than 10 studies. Around 39% of these studies found an increased risk of cancer due to consumption of a given ingredient—including eggs, flour, sugar, wine, and mustard—while 33% noted a decreased risk.

But after analyzing all that data, researchers concluded that the vast majority of the study claims were backed by weak or insignificant statistical support. In other words, despite a ton of research into the connection between diet and cancer, most of those studies don’t yield compelling recommendations about what we should (or shouldn’t) eat for dinner.

Investigators blame “the pressure to publish” for the trend, along with a public appetite for conclusive advice: We want to know what cures or kills us, but nothing in between.

Of course, this isn’t to say that food and cancer aren’t related: A healthy diet is an important element of overall prevention. But, at least right now, there aren’t many specific food items that investigators can point to, with certainty, where the disease is concerned. “I think the most consistent evidence, if anything, was for increased risks [with items like] bacon and salt,” says study co-author John Ioannidis, MD, professor of medicine at Stanford’s Prevention Research Center.